CASTAIC, Calif. - Nearly 2,000 inmates rioted at a Southern California jail, throwing mattresses and banging heads against bunk beds, in an uproar that officials said stemmed from racial tensions. One inmate was killed.

More than 100 inmates were wounded and 20 were hospitalized with serious injuries from the nearly hour-long melee on Saturday, authorities said. Smaller fights broke out for at least four hours after the main brawling ended.

"The motivation appears to be racial tensions and a carry-over of a feud between black and Hispanic gangs," said Deputy Steve Suzuki, a sheriff's spokesman. Two days earlier, a Hispanic gang member was stabbed by a black gang member, he said.

Black and Hispanic inmates were being segregated and a lockdown was ordered systemwide, Sheriff Lee Baca said.